NO fix for Prius Gas Tank Filling Up Issues

[brick]

Originally Posted by cycledrum

Also, I tilt the nozzle handle down which is recommended in diagrams on the pumps.

I tried this yesterday, applying some downward force to the nozzle which presumably creates a little gap between the nozzle and the o-ring on the filler neck. I stopped filling after 6.5 gallons because I started to hear the sound of vapor being forced out. Sure enough, upon inserting the nozzle normally and pumping again it clicked off immediately. So I guess it works but it's probably not a great thing to do since this puts hydrocarbons in the air instead of the charcoal cannister.

Here's to hoping for a bladder-free tank on the 2010!

[edthefox5]

Its not how you hold the lever. Its not the pump. Its not the gas station. The bladder works fine. After my first gas belching I thought about the way I fuel and whats forcing the fuel out or refusing to allow fuel in. Its simple in that there is and will be trapped air in the bladder. You cannot fuel a gas tank with trapped air pockets. Because of the extremely tight vapor emissions recovery system in the tank.
Before you fuel let the tank vent.
When I get gas I open the gas cap. I go inside and let the tank vent for at least 2 minutes. I come back out and slow fill only. I cut a piece of wood 1 inch wide to jam under the gas fill nozzle which fills on slowest mode. On first auto click off hang the pump up. It usually now clicks off really close to what it needs. Do not try to top the tank off!!!!!
Works perfect every time...no premature shut off..no gurgling sounds..no gas belching.
I know I'm defeating the car's vapor emissions mission but whats worse..a little gas fumes or a gallon of gas on the ground.
Please try it. It works.

[All-Purpose Guru]

Folks, I'm an engineer, and I've designed systems that work like gas gauges and battery gauges.

You have *no* idea how much slop there is in a fuel system gauge. Here are some of the issues:

The top of the gauge is NEVER accurate. This is because it is a very bad thing for a customer to go to the gas station, fill the car to "full" and have the gas gauge not indicate "full". This generates service calls and warranty work, which is VERY expensive for Toyota to pay for. Because of this, they engineer "slop" into the gauge.

This is why the first 'cube' is showing a different amount of miles-per-cube than the rest.

The bottom 'cube' and the low-gas alarm are similarly 'fudged'-- they don't necessarily read accurately, because the penalty of having the low end inaccurate is that people are going to be stranded without gas, or worse, driving their Prius on battery-only, which is a *bad* idea.

You also have to understand that the fuel sender-cable-gauge arrangement is not very inherently accurate. Your typical fuel sender in the gas tank is an arrangement roughly like the valve in your toilet-- it floats on the top of the gas and gives a reading that is the height off the bottom of the tank.

You will even find, on some cars, that not even the "middle" of the tank is really the middle-- have you ever noticed on some cars (my '98 Sienna, for example) the first half a tank lasts 3/4 of the time, and the gauge *plummets* for the last half tank? This is that sensor again-- a lot of them are just a float on an arm, and when the tank starts getting empty, the float is moving more than it does when the tank is full-- which means that the "midpoint" of the tank is usually more like 2/3 full.

And don't go on to me about that fancy "digital" gauge-- it's a representation of the voltage coming out of the sensor, nothing more-- and it isn't any more accurate for being digital than a mechanical gauge. Now, on a car with onboard computer systems like the Prius, the actual method of getting the voltage from the sensor to the gauge may be all high-tech and complicated-- but that doesn't make the sensor any more accurate.

You also know that there is a damping, or "delay", in the gauge itself-- it doesn't respond to immediate changes in the fuel level, because if you did that every time you hit the brakes the fuel gauge would bounce around (before they did this, the gauge *did* bounce around-- I had a 68 Impala where I could slam on the brakes and bounce the needle of the fuel gauge off the stop at "F".) This means that you have to wait a bit before you can trust the gauge.

The reality here is that there isn't any exemption here for thinking-- the world kind of expects you to use common sense, and nature has a nasty habit of whacking those that don't.

[All-Purpose Guru]

Originally Posted by edthefox5

Its not how you hold the lever. Its not the pump. Its not the gas station. The bladder works fine. After my first gas belching I thought about the way I fuel and whats forcing the fuel out or refusing to allow fuel in. Its simple in that there is and will be trapped air in the bladder. You cannot fuel a gas tank with trapped air pockets. Because of the extremely tight vapor emissions recovery system in the tank.
Before you fuel let the tank vent.
When I get gas I open the gas cap. I go inside and let the tank vent for at least 2 minutes. I come back out and slow fill only. I cut a piece of wood 1 inch wide to jam under the gas fill nozzle which fills on slowest mode. On first auto click off hang the pump up. It usually now clicks off really close to what it needs. Do not try to top the tank off!!!!!
Works perfect every time...no premature shut off..no gurgling sounds..no gas belching.
I know I'm defeating the car's vapor emissions mission but whats worse..a little gas fumes or a gallon of gas on the ground.
Please try it. It works.

Actually, on my last car, the gas cap specifically said to let the tank vent for several seconds before adding fuel-- I don't remember if the Prius says the same thing.

You're supposed to let it vent for a few minutes, at least-- the barometric pressure inside the tank and bladder may be different from the pressure outside, as well, which means you might have better or worse luck filling the tank depending on the weather and the altitude of the gas station.

[singerlin]

I have an 09 Prius and with the exception of the gas tank issue, I love it. I have filled the gas tank 7 times and it has had the click-off problem 7 times. When I am anticipating putting in 8 or 9 gallons (I never let it go down lower than that in winter living here in the upper midwest), it clicks off at 4 1/2 or 5. It doesn't matter if I am filling it slowly or not. I haven't tried the upside-down gas nozzle trick yet, but will do so the next time I fill up. If I continue putting in a little at a time with it constantly clicking off and listen for the pitch change that indicates it is full, when I pull out the nozzle, air burps back and the gas starts backing up. This does not make me a happy camper.

I do object to the individual who posted the message to fill it up until it shuts off and just go for 300 miles. I want to know what kind of MPG I am truly getting and you cannot get that from the internal gauge. The only way to get it accurately is to fill the tank completely, measure the miles and fill it completely again. If you never know if you have completely filled the tank, you don't know how accurate the MPG is.

[Shawn]

Originally Posted by singerlin

I do object to the individual who posted the message to fill it up until it shuts off and just go for 300 miles. I want to know what kind of MPG I am truly getting and you cannot get that from the internal gauge. The only way to get it accurately is to fill the tank completely, measure the miles and fill it completely again. If you never know if you have completely filled the tank, you don't know how accurate the MPG is.

Knowing how much you actually use in fuel should not be a problem. If my consumption on the screen indicates that I've travelled 400 kilometers since my last fill up and I pump 20 litres of fuel according to the pump or gas receipt than I calculate that I've used 5.0 litres per 100 kilometers. 400 divided by 100 = 4 20 divided by 4 = 5. I've done this numerous times to check the accuracy of the consumption screen and it is always correct.

[eestlane]

Remove the rubber seal at the top of the gas filler pipe and your filling and burping problems will be over.

[richard schumacher]

Remove the rubber seal at the top of the gas filler pipe and your filling and burping problems will be over.

At the cost of increasing evaporative emissions from the tank and water vapor infiltration into the tank. Better to be patient when filling and try another pump if you have a problem.

[diamondlarry]

Originally Posted by singerlin

I have an 09 Prius and with the exception of the gas tank issue, I love it. I have filled the gas tank 7 times and it has had the click-off problem 7 times. When I am anticipating putting in 8 or 9 gallons (I never let it go down lower than that in winter living here in the upper midwest), it clicks off at 4 1/2 or 5. It doesn't matter if I am filling it slowly or not. I haven't tried the upside-down gas nozzle trick yet, but will do so the next time I fill up. If I continue putting in a little at a time with it constantly clicking off and listen for the pitch change that indicates it is full, when I pull out the nozzle, air burps back and the gas starts backing up. This does not make me a happy camper.

I do object to the individual who posted the message to fill it up until it shuts off and just go for 300 miles. I want to know what kind of MPG I am truly getting and you cannot get that from the internal gauge. The only way to get it accurately is to fill the tank completely, measure the miles and fill it completely again. If you never know if you have completely filled the tank, you don't know how accurate the MPG is.

First off, I want to say that I agree with you on everything you said. Secondly, you are wasting your time talking about this here because most of the people here deny there is a problem and will say something like try another pump; it won't help. The only way to solve this problem is for Toyota to wake up and get rid of the bladder like the other car companies did that meet or exceed the emissions level of the Prius. Other than this or the traction control issue, I love my Prius.

[qbee42]

Originally Posted by diamondlarry

First off, I want to say that I agree with you on everything you said. Secondly, you are wasting your time talking about this here because most of the people here deny there is a problem and will say something like try another pump; it won't help. The only way to solve this problem is for Toyota to wake up and get rid of the bladder like the other car companies did that meet or exceed the emissions level of the Prius. Other than this or the traction control issue, I love my Prius.

So, do you suppose that some Prius have this problem, and some don't? This is a serious question. I am one of the posters who properly claim the problem doesn't exist, at least with my Prius. I suspect that is the case with all of the posters who claim there isn't a problem: it just means that there isn't a problem with their Prius and/or gas pumps.

I seriously doubt that we have a conspiracy of Prius owners trying to hide a fueling problem.

To my way of thinking, the problem is either with some Prius, some pumps, or some owners. The hard part is telling the real problem or combination of problems.

Tom